Add warning for non-unique file name schemes (#233)

* Add warning for non-unique file name schemes

* Update README with warning

bulkredditdownloader/file_name_formatter.py

@@ -89,7 +89,14 @@ class FileNameFormatter:
     def validate_string(test_string: str) -> bool:
         if not test_string:
             return False
-        return any([f'{{{key}}}' in test_string.lower() for key in FileNameFormatter.key_terms])
+        result = any([f'{{{key}}}' in test_string.lower() for key in FileNameFormatter.key_terms])
+        if result:
+            if 'POSTID' not in test_string:
+                logger.warning(
+                    f'Post ID not included in this file scheme, so file names are not guaranteed to be unique')
+            return True
+        else:
+            return False
 
     @staticmethod
     def _format_for_windows(input_string: str) -> str:

bulkredditdownloader/tests/test_integration.py

@@ -254,3 +254,18 @@ def test_cli_download_links(test_args: list[str], tmp_path: Path):
     assert result.exit_code == 0
     assert 'in exclusion list' in result.output
     assert 'Downloaded submission ' not in result.output
+
+
+@pytest.mark.online
+@pytest.mark.reddit
+@pytest.mark.skipif(Path('test_config.cfg') is False, reason='A test config file is required for integration tests')
+@pytest.mark.parametrize('test_args', (
+    ['--file-scheme', '{TITLE}'],
+    ['--file-scheme', '{TITLE}_test_{SUBREDDIT}'],
+))
+def test_cli_file_scheme_warning(test_args: list[str], tmp_path: Path):
+    runner = CliRunner()
+    test_args = ['download', str(tmp_path), '-v', '--config', 'test_config.cfg'] + test_args
+    result = runner.invoke(cli, test_args)
+    assert result.exit_code == 0
+    assert 'Post ID not included in this file scheme' in result.output